The present invention relates to compositions for treating fungal activity in plants or soil, containing castor oil, water, at least one surface active agent, optionally pennyroyal oil, and optionally an agriculturally acceptable carrier. The present invention also relates to methods of treating fungal activity in plants or soil, involving administering to the plant or soil an effective fungal treating amount of castor oil, water, at least one surface active agent, optionally pennyroyal oil, and optionally an agriculturally acceptable carrier.
Approximately, 90% of the 2000 major diseases of principle crops in the US are caused by soilborne plant pathogens, resulting in losses in excess of $4 billion/year and fungi are considered the foremost important plant pathogen (Lewis, J. A., and G. C. Papavizas, Crop Protection, 10: 95-102 (1991); Lumsden, R. D., et al., Formulation and delivery of biocontrol agents for use against soilborne plant pathogens, In: Biorational Pest Control Agents, Hall, F. R., and J. W. Barry, Eds., American Chemical Society, Washington, DC, 1995, pp. 166-182; Agrios, G. N., 2005, Plant Pathology, 5th Edition, Elsevier Academic Press, MA). For example, Rhizoctonia solani is a ubiquitous soilborne fungal pathogen causing pre-emergence and seedling damping off, root rot, stunting of plants and aerial blights of economically important crops, forest trees, ornamentals and turfgrasses, as well as decay of postharvest fruits and vegetables (Agrios 2005). Soilborne fungal pathogens have been traditionally controlled using chemical pesticides, some of which deplete non-renewable resources, are inconsistent in efficacies, and are toxic to the environment. As a result, the 1996 “Food and Quality Protection Act” of the United States has dramatically restricted the use of many conventional pesticides upon which the American farmers have long depended. For example, methyl bromide is highly genotoxic and it depletes the ozone; except for critical use exemption, it has been banned for soil fumigation since 2005. Many fungicides, including several alternatives fumigants to methyl bromide (e.g., methyl iodide), are expensive and suspected of introducing new health hazards to agricultural workers (Clifford, B. C., and E. Lester, 1988. Control of Plant Diseases: Costs and Benefits, Blackwell, Oxford, UK; California Dept. of Pesticide Regulation (2010), http://www.cdpr.ca.gov/docs/risk/methyliodide.htm). Also, persistence of many fungicides following their use caused pathogen resistance to several of the fungicides (Delp, C. J., Fungicide resistance in North America, 1988, APS Press, St. Paul, Minn.; Zhao, H., et al., Postharvest Biol. Technol., 56:12-18 (2010)). As a result, eco-friendly management using safer chemicals (i.e., biorationals) are being increasingly sought to control plant diseases.
Thus there exists a need for new compositions and methods to control plant diseases.